# Perimeter Institute Quantum Discussions

This series consists of weekly discussion sessions on foundations of quantum Theory and quantum information theory. The sessions start with an informal exposition of an interesting topic, research result or important question in the field. Everyone is strongly encouraged to participate with questions and comments.

## Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

## Linear optics quantum information and Quantum simulation of many-body

Wednesday Nov 15, 2006
Speaker(s):

In this talk, I will show how to efficiently generate graph states
based on realistic linear optics (with imperfect photon detectors and source), how to do scalable quantum computation with probabilistic atom photon
interactions, and how to simulate strongly correlated many-body physics with ultracold atomic gas.

Scientific Areas:

## Quantum spin Hamiltonian problems and Interactive Proofs

Wednesday Nov 08, 2006
Speaker(s):

Complexity class MA is a class of yes/no problems for which the answer yes\' has a short certificate that can be efficiently checked by a classical randomized algorithm. We prove that MA has a natural complete

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## Quantum Computing without Entanglement?

Wednesday Oct 11, 2006
Speaker(s):

TBA

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## Many Worlds

Tuesday Oct 03, 2006
Speaker(s):

TBA

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## Random bipartite entanglement from W and W-like states

Monday Sep 25, 2006
Speaker(s):

We describe a protocol for distilling maximally entangled bipartite states between random pairs of parties (random entanglement'') from those sharing a tripartite W state, and show that this may be done at a higher rate than distillation of bipartite entanglement between specified pairs of parties (`specified entanglement'').

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## Probability theory --classical, quantum and otherwise

Friday Sep 22, 2006
Speaker(s):

Quantum mechanics is a non-classical probability calculus -- but hardly the most general one imaginable. In this talk, I'll discuss some familiar non-classical properties of quantum-probabilistic models that turn out to be features of {em all} non-classical models. These include a generic no-cloning theorem obtained in recent work with Howard Barnum, Jon Barrett and Matt Leifer.

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## Three Tales of Entanglement

Thursday Sep 21, 2006
Speaker(s):

Entanglement is one of the most studied features of quantum mechanics and in particular quantum information. Yet its role in quantum information is still not clearly understood. Results such as (R. Josza and N. Linden, Proc. Roy. Soc. Lond. A 459, 2011 (2003)) show that entanglement is necessary, but stabilizer states and the Gottesman-Knill theorem (for example) imply that it is far from sufficient. I will discuss three aspects of entanglement.

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## Incorporating Gravity into Bohmian Mechanics: A New Approach

Tuesday Sep 19, 2006
Speaker(s):

My field is the foundations of quantum mechanics, in particular Bohmian mechanics, a non-relativistic theory that is empirically equivalent to standard quantum mechanics while solving all of its paradoxes in an elegant and simple way, essentially by assuming that particles have trajectories.

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## New separations in quantum communication complexity

Wednesday Aug 30, 2006
Speaker(s):

In this talk I will present several new results from joint work with Dmitry Gavinsky, Oded Regev and Ronald de Wolf, relating to the model of one-way communication and the simultaneous model of communication. I will describe several separations between various resources (entanglement versus event coin, quantum communication versus classical communication), showing in particular that quantum communication cannot simulate a public coin and that entanglement can be much more powerful than a public coin, even if communication is quantum.

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## Local quantum dynamics and information flow

Wednesday Jul 05, 2006
Speaker(s):

In order to predict the future state of a quantum system, we generally do not need to know the past state of the entire universe, but only the state of a finite neighborhood of the system. This locality is best expressed as a restriction on how information "flows" between systems. In this talk I will describe some recent work, inspired by quantum cellular automata, about the information strucutre of local quantum dynamics.

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## RECENT PUBLIC LECTURE

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